1. Field of the Invention
The invention relates generally to drilling machine guidance systems and, more particularly, but not by way of limitation, it relates to an improved guidance system for use in horizontal drilling apparatus of the type used in mining operations.
2. Description of the Prior Art
There are numerous prior art guidance systems for use with drilling apparatus, both horizontal drilling machines and vertical or well drilling apparatus. U.S. Pat. No. 3,362,750 discloses a mining apparatus having programmed cutting direction and attitude controls, and this teaching utilizes a comparator for sensing a departure of the cutting machine from its programmed direction thereafter to correct the deviations. The system utilizes a plurality of pendulums and related comparator circuitry for sensing program deviations. U.S. Pat. No. 3,326,008 relates to an electrical gopher which is utilized to bore horizontal cable holes. This device utilizes a plurality of synchro motors to maintain its guidance direction. Still other forms of circuitry are utilized in the prior art, especially that art which is related to position keeping within vertical boreholes and well drilling apparatus; however, none of the prior art approaches are similar to the present circuit apparatus nor do they offer the attendant functions and advantages for operation of a push drill remotely guided through a mineral stratum.